1. Technical Field
This invention generally relates to optical elements, and more specifically relates to mechanisms for high speed switching of optical elements.
2. Background Art
In optical instruments there is a need in many different applications for the ability to rapidly insert and remove optical elements into an aperture or optical beam. Traditionally, this switching has been accomplished by the use of a wheel mechanism that rotates various elements in and out of the aperture.
In wheel mechanisms, optical elements are arranged around the perimeter of a wheel. As different elements are needed, a motor or other driver rotates the wheel, stopping when the desired element is in the optical path. This allows different optical elements to inserted into optical path as desired.
Unfortunately, wheel mechanisms suffer from several significant disadvantages. For example, the amount of time and energy used to switch from one element to another can be unacceptable for many applications. This is an especially significant issue when the wheel switches from one element to another that is on the opposite side of the wheel. In some cases it can be difficult to rotate the wheel fast enough to switch it from one side of the wheel to the other. Additionally, the amount of power required to move the wheel from one end of the other can be excessive. These limitations all arise from the fact that the traditional wheel provides a sequential rather than random access to the elements at the edges of the wheel.
Another difficultly in using traditional wheel solutions is that the rapid movement of the wheel can cause disturbances to the system that can blur the image. This is especially significant in applications that require precise control over the optical system, such as in satellite applications. To compensate for the force disturbances caused by the rapidly moving wheel, traditional approaches have been forced to allow for long settling periods after wheel movement or use of complex force compensation and/or isolation mechanisms that significantly increase the complexity of the system while decreasing the reliability. These mechanisms also require significant power that must be supplied and dissipated, negatively impacting the thermal stability of the device.
Thus, what is needed is an improved optical element switch mechanism that provides for improved switching speed, low power consumption, and reduced disturbances.